This invention relates to improvements in a re-leveling apparatus for an elevator which serves to reposition an elevator cage to re-level the floor of the cage of the elevator when the cage has stopped outside normal floor arrival limits.
In an A.C. elevator, it is sometimes the case that, when a cage stops at a destination floor, the fault of a floor arrival control device or the fluctuation of the characteristic thereof causes the levels of a hall floor and a cage floor to deviate greatly, making it difficult to get on and off the cage. In such a case, the cage floor needs to be brought close to the hall floor as quickly as possible. That is, the operation of automatically repositioning the cage to level the cage floor with the hall floor is carried out. Hereinbelow, this operation shall be termed the `floor re-leveling operation`.
An example of such a floor re-leveling apparatus has hitherto been proposed in Japanese Patent Application Laid-open No. 52-131341.
FIGS. 12 through 14 show the prior-art floor re-leveling apparatus mentioned above. Referring to the figures, letters R, S and T designate a three-phase A-C power sources, and symbols (+) and (-) denote an D-C power source. Numeral 21 indicates an electromagnetic contactor for an up run, which has normally-open contacts 2la-2lc. Numeral 22 indicates an electromagnetic contactor for a down run, which has normally-open contacts 22a-22c. Symbol 23A denotes an ordinary run control device, while symbol 23B denotes a floor arrival control device for controlling the speed of a cage 31 in a floor arrival mode. Shown at numeral 24 is a driving induction motor. A braked wheel 25 is driven by the motor 24, a brake shoe 26 exerts a frictional force on the braked wheel 25, and a brake coil 27 releases the brake shoe 26 from the brake wheel 25 against the force of a spring 28 when energized. The spring 28 presses the brake shoe 26 against the brake wheel 25 owing to the force of the spring 28 when the coil 27 is deenergized. The aforementioned brake wheel 25, brake shoe 26, brake coil 27 and spring 28 form a magnet brake. Numeral 20 designates the sheave of a hoist, and numeral 30 a main rope which is wound round the sheave 20 and to which the cage 31 and a counterweight 32 are coupled. Numeral 33 designates a floor in a hall of a building. Symbols U1a, U1b, U2a and U2b denote up position switches which operate according to the positions of the cage 31, respectively, and which are realized by, for example, installing position switches (not shown) in the cage 31 and cams (not shown) in a hoistway. The operating states of the position switches are shown in FIG. 14, in which hatched parts indicate the `off` sections thereof. Symbols D1a, D1b, D2a and D2b denote down position switches which operate similarly. A floor re-leveling relay 35 has normally-open contacts 35a and 35b, and a normally-closed contact 35c. A floor re-leveling electromagnetic contactor 36 has a normally-open contact 36a, which is associated with a starting resistor 37. Numeral 38 indicates a reset type time-limit relay having a normally-open contact 38a, and numeral 39 also indicates a reset type time-limit relay having a normally-open contact 39a.
Next, the operation of this example will be described.
In a case where the cage 31 performs the up run, the operation of the ordinary run control device 23A energizes the electromagnetic contactor for the up run 21 to close the contacts 2la. Since the floor re-leveling electromagnetic contactor 36 is held energized to close the contact 36a, the motor 24 is fed with electric power. At the same time, the contact 21b is also closed, the brake coil 27 is energized to release the magnet brake, and the motor 24 rotates, so that the cage 31 ascends through the sheave 20 as well as the main rope 30. When the cage 31 has reached the deceleration point of a destination floor, the floor arrival control device 23B operates, and the cage 31 stops upon coming near to the floor 33.
When the ordinary run has ended, the contactor 21 is deenergized to open the contacts 2la-2lc, and the motor 24 is cut off from the power source R, S, T. The brake coil 27 is also deenergized allowing the brake 26 to engage the brakewheel 25 thereby holding the cage 31 at a stationary position. Assuming here that the stop position of the cage be a point a in FIG. 14, the position switches D2a, D2b, D1a and D1b are turned `on`. Soon after the opening of the contact 2lc, the time-limit relay 38 is reset to close the contact 38a, and the floor re-leveling relay 35 is energized by a closed circuit consisting of (+) - (38a) - (D2a) - (D1b) - (35) - (-), so that the contact 35a is closed. Thus, the contactor 21 is energized by a closed circuit consisting of (+) - (35a) - (D1a) - (21) - (-), and the contacts 2la - 2lc are closed, with the result that the motor 24 is fed with power. At the same time, the magnet brake is released, and the cage starts in the up direction. Meanwhile, since the energization of the floor re-leveling relay 35 opens the contact 35c, the contactor 36 is deenergized to open the contact 36a, whereby the starting resistor 37 is inserted in one phase of the motor 24 so as to make the acceleration of the cage in the floor re-leveling mode lower than that in the ordinary run mode.
Subsequently, when the cage 31 has reached a point P in FIG. 14, the position switches D2a and D2b are turned `off`, and the relay 35 is deenergized (the contact 39a of the time-limit relay 39 is kept open for a while after the turn-off of the switches D2a and D2b). Accordingly, the contact 35a opens, and the contactor 21 is deenergized to open the contacts 2la-2lc, so that the power feed to the motor 24 is cut off and that the magnet brake works. Assuming that the cage 31 has stopped at a point b on this occasion, only the position switches D1a and D1b are `on`. Next, soon after the turn-off of the position switch D2b and the opening of the contact 2lc, the time-limit relays 38 and 39 are reset to close the respective contacts 38a and 39a, a closed circuit consisting of (+) - (38a) - (39a) - (D1b) - (35) - (-) energizes the relay 35 to close the contact 35a and turn on the switch D1a, and the contactor 21 is energized, so that the cage 31 is restarted in the same manner as in the start from the point a. Thereafter, when the cage 31 has come to a point Q in FIG. 14, the position switches D1a and D1b are also turned off, and the contactor 36 and the relay 35 are deenergized, whereupon the cage is decelerated in the same manner as in the deceleration from the point P. If, at this time, the cage 31 stops within normal floor arrival limits X, the floor re-leveling operation is completed.
In the prior-art floor re-leveling apapratus constructed as described above, the floor re-leveling operation is realized by the relay circuitry, so that the circuit arrangement becomes complicated and expensive. Another problem is that, when the cage stop position deviates greatly from the normal floor arrival limits, the floors cannot be leveled by the single floor leveling operation. A further problem is that, when the cage stops near the section of the normal floor arrival limits, the cage enters the section of the normal floor arrival limits before a sufficient increase in the speed thereof, so the floor arrival driving performance of the apparatus is inferior.